This invention relates to a method and apparatus for transmitting digital information signals capable of being emitted from signal transmitters, together with an address signal preceding the information signals, and indicating a signal receiver capable of accepting the information signals in any time sequence. The information signals are transmitted over switching apparatus toward the signal receiver designated by the address signal associated therewith.
The technique of transmitting information signals from a signal transmitter to a signal receiver, together with an address code designating the information signal receiver intended for acceptance of the information signal in question, has been previously disclosed ("NTF" 40 (1971), pp. 115-118). Such information signals, each provided with an address code, are each transmitted in a given time segment of a pulse frame comprising a prespecified number of time segments, whereby the time segments appearing with the same time position in successive pulse frames belong to a given time slot. Although with this information signal transmission no information must be stored indicating in what time slot the information signals intended for a signal receiver must be transmitted, nevertheless, the information transmission system in question is limited in its transmission capacity by the number of time slots present in each pulse frame, because only the same number of connections can be established is there are time slots within a pulse frame on the telecommunication circuit.
With reference to the above mentioned commonly known address code modulation system, it is known ("NTF" 40 (1971), pp. 119, 120) to transmit information signals in a mobile radio network in such a manner that always a prespecified number of bits are combined into a block and sent together with an address code word to a called station in a time slot detected as free within a frame comprising a specified number of time slots. However, this occurs in such a manner that a specified portion of the group of bits are transmitted in appropriate time positions of successive frames. This, however, provides no information as to what happens when the signals are switched.
It is an object of the invention to provide a method of and apparatus for transmitting in a relatively simple manner information signals emitted from signal transmitters, together with address signals indicating the signals receivers designated to accept the information signals, over switching apparatus toward the designated signal receiver and, at the same time increasing the number of communication links extending over the switching apparatus.